Surfactants have long been used to enhance the efficacy of contact and systemic herbicides. Surfactants may provide enhanced penetration, wetting, or sticking characteristics in formulations containing surfactant and herbicide, or assist in dissolving herbicides in carriers such as water or oil. Some surfactants are often themselves herbicidal agents which act by contact or systemic action. In general, the mechanism of action of formulations containing surfactants in plants, and the manner of optimizing the choice of surfactant for use with a particular plant species, weed species, and herbicide, is not well understood.
A variety of surface-active agents (i.e., surfactants) derived from fatty acids, fatty alcohols, and esters and polyethoxylated condensate products thereof have been used as adjuvants in herbicidal or plant growth regulator formulations. For example, C.sub.5-22 aliphatic carboxylic acids have been used to increase the solubility of a proton acceptor amino medicament or herbicide in oil in U.S. Pat. No. 3,172,816. Polyunsaturated linoleic or linolenic acids are combined with the grass herbicide "Barban" to combat wild oats in U.S. Pat. No. 4,134,754. Also, C.sub.6-18 saturated fatty alcohols are combined with isopropyl-N-(3-chlorophenyl) carbamate to provide a composition for inhibiting tobacco sucker development in U.S. Pat. No. 3,438,765. U.S. Pat. No. Re. 30216 describes a mixture of C.sub.6-18 saturated fatty alcohols and maleic hydrazide derivatives for tobacco sucker control, the resulting compositions also optionally containing reaction products of ethylene oxide with saturated long chain fatty acids as surface-active agents. Methyl esters of C.sub.6-12 saturated fatty acids are mixed with fatty acid esters of polyethoxylated sorbitan (wherein the fatty acid contains about 10 to about 18 carbon atoms and wherein there are about 5 to about 80 ethoxy moieties per molecule) to provide chemical pinching agents in U.S. Pat. No. 3,620,712. Lower alkyl esters of saturated and unsaturated C.sub.6-18 fatty acids are mixed with isopropyl-N-(3-chlorophenyl) carbamate to provide tobacco desuckering compositions in U.S. Pat. Nos. 3,326,664 and 3,340,040, and are used alone and in combination with isopropyl-N-(3-chlorophenyl) carbamate as tobacco desuckering compositions in Tso et al, "Inhibition of Tobacco Axillary Bud Growth with Fatty Acid Methyl Esters", J. Agr. Food Chem., 13, 78 (1965). Condensates of ethylene oxides and various alcohols have been used in herbicide formulations, for example, in U.S. Pat. Nos. 3,990,884 (lauryl alcohol), 3,954,439 (nonyl phenol), and 4,084,956 (various saturated fatty alcohols, and oleyl alcohol, in combination with the grass herbicide "Barban").
Various surface active agents containing condensates of ethylene oxide and unsaturated fatty acids have been used in non-agricultural applications, for example, as anti-caking agents in cosmetics. Also, polyethoxylated C.sub.12-26 saturated and unsaturated fatty acid esters have been reported for use as anti-caking and wetting agents in pesticidal formulations containing the non-herbicidally active compound 2-heptadecyl-2-imidazoline, in U.S. Pat. No. 3,100,174.
Despite all of the above reported combinations of herbicides or plant growth regulators with saturated or unsaturated fatty acids, fatty alcohols, and esters and ethylene oxide condensates thereof, and the above-described combination of the pesticide 2-heptadecyl-2-imidazoline with polyethoxylated unsaturated fatty acid esters, no broadleaf foliar herbicide formulations containing condensates of ethylene oxide and unsaturated fatty acids have been previously reported. Also, no broadleaf foliar herbicidal formulations containing condensates of ethylene oxide and unsaturated fatty amines, unsaturated fatty amides, or unsaturated fatty alcohols have been reported.